Desiccant materials for air conditioning applications - A review

Abstract

Desiccants are a group of adsorbent materials that have a great affinity for water vapour. Due to this merit, desiccant material can produce hot and dry air which can be used for the drying process as well as in air-conditioning applications to minimize the latent heat load. A good desiccant must have better moisture absorption capability as well as lower regeneration temperature. The moisture absorption capability basically depends upon the desiccant characteristics like pore volume, apertures size and void fraction. Depending upon normal physical state, desiccants can be either solids or liquids. Solid desiccant materials such as silica gel, natural zeolites, molecular sieves, activated alumina, synthetic polymers are highly porous in nature and adsorb water by using mechanisms of chemical adsorption. Liquid desiccants such as Calcium chloride, tri-ethylene glycol, and lithium chloride are generally very strong solutions of ionic salts and their behaviour is controlled by changing its temperature and concentration. This paper presents a detailed study on different solid, liquid and composite desiccant which combine two or more desiccant materials for better properties and performance. This review has a great significance for the research and technical development in the field of desiccant dehumidification and air-conditioning technology.